Aviation safety investigations & reports

APU event - Darwin Airport, NT, 11 October 2006, VH-ZXE

Summary

On 11 October 2006, at approximately 1420 Central Standard Time,
a Boeing Co 767-336 was departing from bay 3 at Darwin Airport, NT
for Brisbane Airport, Qld. Just prior to taxi, an auxiliary power
unit (APU) fire warning activated with associated indications. The
crew carried out the APU FIRE checklist items and the APU fire
warning message extinguished and the aural APU fire warning
ceased.

Company engineering and Aviation Rescue and Fire Fighting (ARFF)
personnel performed an external visual inspection of the APU area
and advised the crew that there were no signs of a fire from the
APU. The aircraft was returned to the departure gate.

The aircraft was returned to service under the provision of the
B767 minimum equipment list item applicable for the operation of
the aircraft with an inoperative APU.

During overnight maintenance in Sydney, company engineering
staff found the remnants of a significantly-charred cloth rag
located on top of the aircraft's APU.

A number of safety actions were carried out or proposed by the
operator as a result of this incident, including:

amendments to the maintenance documentation for clearance
closure inspections

action to reinforce the responsibility and importance of the
clearance closure inspections and to remind maintenance staff of
the company's 'Safety over Schedule' principles

the review of the suitability of equipment to gain access to
all areas of the APU compartment

a review of relevant licensed aircraft maintenance engineer
training.

In addition, as a result of this incident, the ARFF changed its
procedures to include that, until an ARFF response was called to a
'STOP', either an aircraft engineer or ARFF member was required to
inspect the relevant aircraft compartment or area where a fire had
occurred, an aircraft's fire warning system had activated, or an
onboard fire extinguisher had been activated.